qtdeploy is intended to be used for deploying and therefore will run qtrcc, qtmoc, qtminimal and do the actual bundling of your binary. the -fast flag re-uses the cached rcc_* moc_* minimal-* files and will also not re-run the actual bundling process. this works for the desktop targets but not for the mobile targets, therefore I made it optional.

In what world would "fast" mean "do things faster with no downsides"? ;)

It's a trade-off between deployment speed and quality, like compiler optimizations.